The present invention relates to an air bag system in which a folded air bag and an inflator are supported on a retainer, so that the air bag is inflated to be deployed into a passenger compartment of a vehicle by a gas produced by the inflator at the time of collision.
An air bag adapted to be deployed into a passenger compartment of a vehicle by a gas supplied from an inflator at the time of collision of the vehicle is provided with a vent hole, and when an internal pressure of the inflating air bag increases as a result of restraining an occupant, the gas so supplied is then released through the vent hole so as to decrease the tension of abase fabric of the air bag, whereby not only is the occupant restrained gently but also the breakage of the base fabric is prevented.
In the event that the vent hole is constituted by a simple hole opened in the base fabric, since the gas leaks from the vent hole in a process where the air bag is inflated by the gas supplied from the inflator, there is a possibility that the deployment of the air bag will be delayed.
In the Japanese translation of the PCT patent application, JP-T-2000-515090 (the term “JP-T” as used herein means a published Japanese translation of a PCT patent application), an air bag system is described where the leakage of gas in the deployment stage is prevented by sealing a vent hole with a sealing member. When an internal pressure of the inflating air bag increases as a result of restraining an occupant, a brittle area formed on the sealing member breaks so as to allow for the leakage of the gas. In this conventional air bag system, however, since the special sealing member is needed to close the vent hole in the air bag, the increased number of components and the increased number of man-hours required in processing the air bag system cause the problem of increased production costs.